1. Field of the Invention
The present invention relates to a real-time (instantaneous) vehicle anti-theft warning, notification and tracking system that eliminates false alarms by comparing a calculated displacement profile representative of the characteristics of a measured displacement (or apparent displacement) of a vehicle with predetermined displacement profiles. The present invention employs a displacement sensor with a unique monitoring program that measures the rate-of-change, direction, and/or duration of displacement of a vehicle (e.g., an automobile or aircraft) over time, and accurately characterizes real and virtual displacements based on the comparison of the calculated displacement profile with the predetermined displacement profiles.
2. State of the Art
Private/commercial vehicles and items in vehicles continue to be stolen despite the prevalence of factory equipped or after-market warning systems. Current security systems fail to protect vehicles from being stolen and/or violated by thieves because the systems have certain limitations. Most alarm systems are fundamentally passive, i.e., they generate an alarm signal (e.g., a siren) in the vicinity of the vehicle only. As such, an owner or law enforcement agency cannot respond in a timely manner to an imminent theft or a theft in progress. Quick response is vital to preventing such thefts, particularly in view of the use of tow trucks and lift trucks in vehicle thefts.
Vehicles equipped with motion sensors are prone to generating false alarms because they cannot with certainty differentiate between the movement of a vehicle caused by a non-theft event (e.g., a seismic event, movement due to melting ice or snow, someone sitting on the vehicle) and an actual theft in progress (e.g., the lifting of the vehicle to tow it away or an unauthorized entry of the vehicle). These false alarms have diminished the significance of any vehicle alarm sounding or communicating with an owner or law enforcement agency; bona fide vehicle alarm activations are often ignored by the police, and the public. Quoting an authority in security systems, Mr. David Bell, from the November 1996 issue of Security Products, a monthly trade publication: "Alarms have a difficult reputation. They've been fitted in the after-market for a while, and the poor security and poor reliability of many products have given them a bad name. Obviously, false alarms are the worst problem--people have gotten so used to them that they pay no attention when a car alarm is sounding." These simple and costly facts are clearly indicative that current alarm systems need to be improved. Security systems that can track vehicles by remote means and/or immobilize them by shutting off critical subsystems, e.g., ignition systems, are largely ineffective because of their passive (delayed) operating characteristic. Responding in seconds to a bona fide theft is vital in successfully thwarting the efforts of a thief. But, more often than not, hours pass before the owner of a vehicle becomes cognizant that his/her vehicle has been stolen or violated, and only then are the police notified to institute various countermeasures. These delayed countermeasures are futile in saving the vehicle or vehicle contents from theft, since too much time elapses between the theft and the notification of the police. The vehicle, for example, may already have been dismantled, or placed in the hold of a ship for shipping to a location for resale. Time, which is absolutely critical in this situation, is lost before the police are notified of the stolen vehicle, either by the owner or by a private servicing security entity. The vehicle is simply lifted up by a tow truck in a matter of seconds and transported away; then, while en route or at a remote location, the vehicle's power supply is disconnected, including the back-up (hidden) power supply used for the security system. A thief requires very little time to secure the vehicle, transport it away, and inactivate the receiving and transmitting electronic systems that either track or immobilize the vehicle.
Proactive alarm systems have been developed that can, for example, communicate with the vehicle owner and/or law enforcement agencies via wireless notification methods (e.g., pagers, cellular telephone, etc.). These systems rely on conventional detection techniques to sense the occurrence of a possible theft event. In light of the serious technological shortcomings with conventional detection techniques outlined above, these security systems cannot be relied upon to communicate accurately, immediately and directly with the police; too many false alarms are generated.
U.S. Pat. No. 4,929,925 to Bodine et al. ("Bodine"), the disclosure of which is incorporated herein by reference, discloses an alarm system that monitors several regions in and around a vehicle utilizing ultrasound. The system of Bodine is based on measuring the distance between a sensor and a fixed location, for example, the ground beneath the vehicle, and triggering an alarm if a subsequent measurement of the same distance indicates movement of the vehicle such that the distance between the sensor and the fixed point has changed beyond a threshold amount. Specifically, a hood transducer first measures the distance between the hood transducer and the ground when the vehicle is initially parked (the "initial value") and the measurements are periodically taken to measure the same distance at a later time (the "current value"). If the current value is greater than the initial value, this is an indication that either the automobile or the hood of the automobile has been lifted, and an alarm is activated. Thus, the system of Bodine cannot discriminate between an actual theft event (the lifting of the car for towing) and a non-theft event (a seismic tremor or vibration caused by a truck passing near the vehicle). Further, since Bodine only detects an increase in distance between the sensor and the ground, downward movement of the vehicle (for example, when someone sits in the vehicle) is not detected by the hood transducer.